Interconversion between different forms of energy is a crucial capability in a diverse range of technologies from interplanetary probes to nano-fabricated micro-electronic mechanical systems (MEMS) and everything in between. Flexoelectricity is a linear coupling between orientational deformation (caused by, for example, mechanical flexure) and electric polarization. Flexoelectricity is a unique property of orientationally ordered materials, of which nematic liquid crystals (NLCs) are the best known example. The original flexoelectric effect, or coupling between electric polarization and elastic flexure in NLCs was first predicted almost 40 years ago. For common calamitic (rod-shaped) liquid crystal molecules (the type of compound ubiquitous in liquid crystal display applications), the flexoelectric effect is very small and effectively unusable for many applications of, for example, electro-mechanical energy conversion.
To date, flexoelectric coefficients, which characterize the flexoelectric effect, have mainly been measured using indirect methods such as analyzing optical effects produced by electric field induced director distortions. Usually, hybrid aligned cells are used, where either the sum or difference (depending on the cell geometry) of the coefficients may be obtained. Such methods often require knowledge of various material parameters such as birefringence, dielectric and elastic constants, and anchoring energies which, ideally, should be independently measured. Published data on flexoelectric coefficients should be handled, however, with some care as various authors have obtained different values from the same experimental data sets using different evaluation techniques. This is perhaps not surprising given how small the coefficients are for calamitic NLCs.
Further limitations and disadvantages of conventional, traditional, and proposed approaches will become apparent to one of skill in the art, through comparison of such systems and methods with the present invention as set forth in the remainder of the present application with reference to the drawings.